DOSAGE COMPENSATION OF GENES ON THE LEFT AND RIGHT ARMS OF THE X CHROMOSOME OF DROSOPHILA PSEUDOOBSCURA AND DROSOPHILA WILLISTONI

摘要

We have investigated the occurrence of dosage compensation in D. willistoni and D. pseudoobscura , two species whose X chromosome is metacentric with one arm homologous to the X and the other homologous to the left arm of chromosome 3 of D. melanogaster . Crude extracts were assayed for isocitrate dehydrogenase (XR), glucose-6-phosphate dehydrogenase (XL?), 6-phosphogluconate dehydrogenase (XL?), and α-glycerophosphate dehydrogenase (chromosome 2 ) in D. willistoni , and for esterase-5 (XR), glucose-6-phosphate dehydrogenase (XL?), 6-phosphogluconate dehydrogenase (XL?) and amylase (chromosome 3 ) in D. pseudoobscura . Our results indicate that a mechanism for dosage compensation is operative in both arms of the X chromosome of these two species.